Heavy, Persistent Marijuana Use Impairs Social Mobility and Economic Status

Researchers in New Zealand studied their subjects for almost four decades to determine effects of long-term marijuana use on social mobility. stockphoto4u/Getty Images

The past few years have seen a spate of laws in the United States legalizing or decriminalizing the possession of marijuana for recreational use. A 2013 study found marijuana to be the most-used illicit drug in the U.S. and that the perceived risk associated with marijuana is on a rapid decline in kids aged 12 to 17.

But as with the legalization of any substance, deregulating pot will involve a bunch of unknown public health and social implications, which is why a new study published in Clinical Psychological Science is so timely.

This long-term study spanning four decades tracked the marijuana use in over a thousand kids born in 1972 and 1973 in Dunedin, New Zealand, from birth until age 38. Participants represented a wide range of socioeconomic and health backgrounds, and had regular follow-up examinations (referred to in the study as "waves") every two to six years. The researchers looked at the socioeconomic mobility of the 947 subjects who participated in three or more waves in the two decades of adulthood between ages 18 and 38.  The number of waves in which participants reported regular marijuana use turned out to have a big effect on more than just their health.

Researchers found that subjects who smoked pot four or more times per week ended up in less-skilled, worse-paying jobs than their parents, regardless of other factors such as lower IQ, less motivation to achieve, more impulsivity, more antisocial behavior, because they were from a lower social class in childhood, or because they have been convicted for a cannabis-related crime.  

"Even after accounting for these and other factors, we still see a relationship between regular, long-term cannabis use and social and economic problems," says lead author Magdalena Cerdá, of the University of California, Davis Health System. "Persistent marijuana users had more troubles with credit, debt, lying to get a job, or intimate partner violence. By middle age, they had also suffered from more financial problems and relationship conflict, in addition to more troubles at work."

These are trends we expect to see in people with alcohol dependence, but though alcohol may be worse for your physical health than marijuana, that's not the case for your finances. Those with cannabis dependence seemed to have even more problems with debt and cash flow, being able to afford food, or low credit scores, than those with alcohol dependence.

In light of this study, should we rethink all the legislative decisions we've been making about pot legalization? According to marijuana legalization advocate organization NORML, the findings of this study are useful, but does not mean pot should be regulated any more strictly than alcohol.

"Cannabis is a mood-altering substance with some risk of abuse potential," says Paul Armentano, deputy director of NORML. "Distinctions ought to be made between cannabis use and abuse, just as we make similar distinctions with alcohol. Unfortunately, a legal environment in which cannabis is criminalized is not conducive to making such distinctions — instead conflating all use with abuse."

But in the face of more prevalent cannabis legalization and use, the researchers warn that we shouldn't walk into it without preparing for the possible social consequences.

"This study highlights the importance of investing in the prevention of regular cannabis use and in early treatment of cannabis addiction," says Cerdá. "Preventing regular, long-term cannabis use can have important implications for how well people do in their lives, their families, their work, and their communities."